1. Field of the Invention
This invention relates to a trunk circuit for an exchange and more particularly to a trunk circuit for an exchange comprising conference trunks.
2. Description of the Prior Art
As is well known, the prior art exchanges have had a plurality of internal office trunks and some conference trunks therein. The internal office trunks and the conference trunks, however, were provided independently of each other, and the internal office trunks functioned only for their own operation. In the same way, the conference trunks were used only when a conference was held.
Therefore, when the conference trunks were not in use and requests for extension calls occurred, the conference trunks were not used at all, even if the quantity of the extension calls was more than the capacity of the internal office trunks.
Moreover, since it has been customary that the number of available connections to one conference trunk has usually been four or five, when a conference was held by more than six subscribers, it was impossible to use the conference trunk.